Liquid mercaptan polymers having at least two terminal mercaptan groups can be easily cured at room temperature to rubber elastomers having excellent resistance to weathering, oil, ozone, and water. Because of these properties polymers having at least two terminal mercaptan groups have been widely used as sealants and adhesives as well as in many other applications.
However, even though mercaptan liquid terminated polymers may be cured to elastomers having very desirable properties; they have, in the past, suffered the disadvantage that a "curing agent" had to be added just prior to use.
Because of this disadvantage, it is not surprising that prior art workers have attempted to develop curing systems wherein the mercaptan-terminated liquid polymer could be formulated with curing agents and the resulting composition cured without further admixture of any ingredients by merely depositing the composition in the location where it is to be used. Such a onepart system is exemplified in U.S. Pat. No. 3,225,017 wherein a liquid polysulfide polymer is cured by merely exposing it to an atmosphere containing moisture thus allowing the polysulfide polymer to be cured without agitation or further mixing with other ingredients. U.S. Pat. No. 3,225,017 accomplishes the foregoing by adding an alkali metal or alkaline earth metal peroxide together with an alkaline hygroscopic stabilizer.
The curing agents in U.S. Pat. No. 3,225,017, although being generally satisfactory, do have one serious disadvantage in that such curing agents require a great deal of moisture thereby preventing their use in relatively arid climates having low relative humidity such as climates found in Southern California. Cures are especially slow when calcium oxide is used as the only alkaline stabilizer.